Any way to fix this cylinder?
Ok to turn my comment into an actual answer: 

Within Edit Mode: 
Select the vertices you want to delete by pressing C and clicking LeftMouseButton on the ones you wish to delete. Use the mouse wheel to change the size of the brush(press rightmousebutton confirm selection), OR use the box-select tool, B, and drag. Afterwards press X, then V.Then you'll want to exturde the top ring of vertices using ALT+Right click, which is used to select loops.
 do ALT+RightMouseButton anywhere between two vertices on the top loop to select the loop(the red lines illustrate some examples of where you can ALT right click). Once selected press E to extrude. It will be automatically stuck along the local Z axis. If you don't want that press Z again. Press LeftMouseButton to confirm placement.  

Related Links:
https://www.blender.org/manual/modeling/curves/editing/introduction.html?highlight=extrude#extending-curves 

How to extrude outwards? 

https://www.blender.org/manual/modeling/meshes/mesh_structures.html#loops